Mars by Moonlight

Of course, Mars has no reasonable-sized moon to light the night or add romance to a lover’s stroll. Its two small companions hasten across the sky like fireflies and the surface below remains dark and cold, but there are degrees of cold, and the THEMIS Infra-Red (IR) Camera on NASA’s Mars Odyssey spacecraft is sensitive to the different wavelengths of IR light, from which we can measure the surface temperature both at night and day.